Chloroaniline, e.g., m-chloroaniline, is typically prepared by chlorinating nitrobenzene and reducing the resulting m-chloronitrobenzene product. The intermediate compounds formed in this process are chemically related to known explosive materials, particularly 2-chloro-4-nitrotoluene, and production of m-chloroaniline by this route poses potential hazards.
Since it is known to prepare haloaniline by reacting alkali metal amide with halobenzene in liquid ammonia, as described, for example, in an article entitled "Low Temperature Amination of Aromatic Polyhalides", Wotiz et al., Journal Organic Chemistry, Vol. 24, pp. 595-598 (1959), it was thought that this procedure might be a more viable route to m-chloroaniline production. Although the process described by Wotiz et al enables the production of m-chloroaniline by low temperature amination of o-dichlorobenzene, the yield of m-chloroaniline is disappointingly low with inordinately long reaction times. In addition, objectionable quantities of undesirable o-chloroaniline and p-chloroaniline isomers are also produced. For example, Wotiz et al reports an m-chloroaniline yield of only 26 percent after 16 hours reaction time, when preparing m-chloroaniline by reacting sodium amide with o-dichlorobenzene in liquid ammonia.
An improved process has been found which enables the production of haloaniline, e.g., m-chloroaniline, in high yield and in shorter reaction times than heretofore believed possible.